Index: trunk/test/unit/org/openstreetmap/josm/data/osm/NodeGraphTest.java
===================================================================
--- trunk/test/unit/org/openstreetmap/josm/data/osm/NodeGraphTest.java	(revision 12478)
+++ trunk/test/unit/org/openstreetmap/josm/data/osm/NodeGraphTest.java	(revision 12478)
@@ -0,0 +1,79 @@
+// License: GPL. For details, see LICENSE file.
+package org.openstreetmap.josm.data.osm;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertTrue;
+
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.List;
+
+import org.junit.Rule;
+import org.junit.Test;
+import org.openstreetmap.josm.testutils.JOSMTestRules;
+
+import edu.umd.cs.findbugs.annotations.SuppressFBWarnings;
+
+/**
+ * Unit tests of the {@code NodeGraph} class.
+ */
+public class NodeGraphTest {
+
+    /**
+     * Setup test.
+     */
+    @Rule
+    @SuppressFBWarnings(value = "URF_UNREAD_PUBLIC_OR_PROTECTED_FIELD")
+    public JOSMTestRules test = new JOSMTestRules();
+
+    /**
+     * Unit test of {@link NodeGraph#buildNodePairs} and {@link NodeGraph#eliminateDuplicateNodePairs}
+     */
+    @Test
+    public void testNodePairs() {
+        assertTrue(NodeGraph.buildNodePairs(Collections.emptyList(), true).isEmpty());
+        assertTrue(NodeGraph.buildNodePairs(Collections.emptyList(), false).isEmpty());
+
+        Way w1 = new Way(1);
+        Way w2 = new Way(2);
+
+        Node n1 = new Node(1);
+        Node n2 = new Node(2);
+        Node n3 = new Node(3);
+
+        Node n4 = new Node(4);
+        Node n5 = new Node(5);
+        Node n6 = new Node(6);
+
+        w1.setNodes(Arrays.asList(n1, n2, n3));
+        w2.setNodes(Arrays.asList(n4, n5, n6, n4));
+
+        w1.setIncomplete(false);
+        w2.setIncomplete(false);
+
+        List<Way> ways = Arrays.asList(w1, w2);
+
+        List<NodePair> l1 = NodeGraph.buildNodePairs(ways, true);
+        List<NodePair> l2 = NodeGraph.buildNodePairs(ways, false);
+
+        assertEquals(Arrays.asList(
+                new NodePair(n1, n2),
+                new NodePair(n2, n3),
+                new NodePair(n4, n5),
+                new NodePair(n5, n6),
+                new NodePair(n6, n4)
+                ), l1);
+
+        assertEquals(l1, NodeGraph.eliminateDuplicateNodePairs(l1));
+
+        assertEquals(Arrays.asList(
+                new NodePair(n1, n2), new NodePair(n2, n1),
+                new NodePair(n2, n3), new NodePair(n3, n2),
+                new NodePair(n4, n5), new NodePair(n5, n4),
+                new NodePair(n5, n6), new NodePair(n6, n5),
+                new NodePair(n6, n4), new NodePair(n4, n6)
+                ), l2);
+
+        assertEquals(l1, NodeGraph.eliminateDuplicateNodePairs(l2));
+    }
+}